In the flotation operation, there are not only a number of changes, but also a change in quality. Therefore, the calculation includes the yield γ (%), weight Q (t / h), metal amount P (t / h), recovery ε (%), work recovery E (%), grade β of each product. (%)Wait. The weight and yield are collectively referred to as the ore distribution index; the metal amount, recovery rate, and operation recovery rate are collectively referred to as the metal amount distribution index; the grade is called the calculation index; sometimes, for some special needs, the supplementary indicator is used separately, that is, the enrichment ratio i And the ratio of mineral processing is K.
In any process, it is necessary to know certain known conditions (known conditions for calculation) in order to perform the full process calculation. These known conditions include: the number of original indicators, the allocation of the original number of indicators, and the selection of the original indicator values. In the calculation of the crushing and grinding process, since the process is simple, only the yield and the weight are calculated, so the original indicators required are small. However, the selection process is different. First, the process is complicated. Second, there are many projects that need to be calculated (especially for polymetallic mines). If these problems are not solved before calculation, the process of sorting cannot be correctly performed.
In the 1970s, foreign countries successfully developed computer programs for the calculation of beneficiation processes, which were customarily called material balance packages. In the early 1980s, China began research in this area, and the research results can be divided into three categories:
(1) Computer programs for design;
(2) Material balance program package for process verification;
(3) A universal material balance package that can be used for both process identification and design.
1 Determination of the number of original indicators
Process calculations are performed by unjoining the cubic program. To solve the cubic program, the known number (that is, the number of original indicators) can not be much, and if it is too much, it may become a contradiction equation; on the contrary, the known number can not be less, and if it is less, it will become an indeterminate equation. Mathematically, the calculation result can be negative, but it is not possible in production. Therefore, it is important to determine the number of original indicators required before the process is calculated.
The number of original indicators can be determined as follows:
Where Np is the number of original indicators (excluding known feed indicators); C is the calculated component (part of the process calculation, if the process only calculates the weight of the product, such as crushing, grinding process, then C = 1; The process must calculate the weight of the product and calculate the content of various metals in the product, then C = 1 + e); e is the number of metal species involved in the process calculation, such as single metal ore e = 1, two metal ores e = 2,..., and so on; np is the number of sorting products in the process (excluding the number of mixed products); ap is the number of sorting jobs in the process (excluding the number of mixed jobs).
It is known from the above formula that, when the ore indicator is known, the number of original indicators required for the calculation process is equal to the difference between the calculated component multiplied by the number of sorting products in the process and the number of sorting operations.
2 Distribution of the number of original indicators
The most commonly used indicators for the flotation process are gamma (yield), beta (grade), ε (recovery) and Q (mineral).
If the original indicator uses the γ, β, ε calculation process, the allocation of the original indicator number is:
For single metal ore:
Where Np is the number of original indicators; Nγ is the number of yield indicators calculated in the process; Nβ is the number of grade indicators calculated in the process; Nε is the number of recovery indicators calculated in the process.
It is known from the above formula that the sum of the various index numbers (ie, Ny, Nβ, Nε) must be equal to the original index number Np. Otherwise, in the process calculation, there is no contradiction equation, or an indeterminate equation. Moreover, the number of Nγ, Nβ, and Nε cannot be arbitrarily determined, and each has a certain range, namely:
For polymetallic ore:
In the formula, β and ε are respectively the grade and recovery rate of the first metal ore; β' and ε' are the grades and recovery rates of the second metal ore, respectively.
In the calculation of the flotation process, γ is generally not used as the original index. Since flotation is continuous operation, it is difficult to measure the yield (γ) value, and it is difficult to measure the weight (Q) of each flotation product, and it is difficult to measure. Therefore, it is usually the case that β (especially the process of the concentrator), or a combination of β and ε (such as industrial design) is used as the original indicator.
8. 8. 3 Selection of original indicator values
The selection of the values ​​of various original indicators shall be based on the values ​​provided in the ore dressing test report, and reference shall be made to the production materials of the ore dressings with similar ore properties. Pay attention to the following points when choosing:
The original indicator selected should be the most stable, most influential and must be controlled indicator of production.
For the selection of the two products, the concentrate grade and recovery rate should be selected, especially the grade and recovery rate of the final concentrate; the selection of the three products, in addition to selecting the concentrate grade and recovery rate, also choose The yield and grade of the ore; the selection of the four products, in addition to the selection of concentrate grade and recovery rate, but also select the secondary concentrate grade and recovery rate, the yield of the middle mine and the recovery rate of tailings.
In a sorting product, γ, β, and ε cannot be used as the original indicators at the same time. Only γ, β, or β, ε are the original indicators. Because the three are functional relations with each other, the second one can be found. three.
When determining the original indicator values, the values ​​provided in the ore dressing test report should be carefully and comprehensively analyzed. If the ore grade of the test ore sample is in error with the ore grade provided by the mining design, and exceeds 10% to 15%, the representativeness of the test ore sample should be reviewed first, and only the original ore grade is found to have errors, and other representative figures are good (such as The particle size characteristics, surrounding rock properties, mineral types, etc., the values ​​provided in the test report can still be used as the basis for selecting the original index values, but the final concentrate grade and recovery rate should be appropriately adjusted. Otherwise, re-sampling is required for the beneficiation test.
8. 8. 4 Calculation of flotation process
Take the calculation of two product processes of single metal ore as an example. The process is shown in Figure 1.
Figure 1 Single metal ore two product selection process
Number of original indicators (known to the mine indicators):
Distribution of the number of original indicators:
There are two common allocation schemes:
Scheme I: β2, β3; Scheme II: β2, ε2
According to Scheme I, the yield of each product is calculated as follows:
Untie the cube program:
Calculated according to scenario II:
The yield of each product is:
The yield of each product is:
The recovery rate of each product is:
Ε2 and ε3 of scheme I are:
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